.frame {
  position: absolute;
  width: 400px;
  height: 400px;
  inset: 0;
  margin: auto;
  border-radius: 2px;
  box-shadow: 1px 2px 10px 0px rgba(0, 0, 0, 0.3);
  overflow: hidden;
  background: #de4738;
  color: #fff;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

.pixel {
  float: left;
}
.pixel input {
  display: none;
}
.pixel label {
  box-sizing: border-box;
  display: block;
  width: 20px;
  height: 20px;
  border: 1px solid #e24e3f;
  cursor: pointer;
}
.pixel label:hover {
  background-color: #e24e3f;
  border-color: #fff;
}
.pixel input:checked ~ label {
  background-color: #fff;
  border-color: #fff;
}